Is NutriCare | INFINITY DNA-Test useful for fatigue?

The NutriCare | INFINITY DNA-Test is marketed to provide personalized nutrition and lifestyle recommendations that might help with fatigue. However, the scientific evidence for this is weak. The genetic variants mentioned in the context (e.g., for vitamin D metabolism or caffeine breakdown) typically have small effect sizes and are not deterministic. Fatigue has many potential causes (iron deficiency, thyroid function, sleep quality, stress) that a DNA test alone cannot address. At best, this test can serve as a supplementary lifestyle tool, but it does not replace medical evaluation. The evidence is mostly based on marketing claims, not on clinical studies demonstrating benefit for fatigue. A blood test (e.g., for TSH, ferritin, vitamin D) would often be more informative.